The invention relates to a fixed ratio planetary type traction roller transmissions whose traction surfaces are in engagement with each other for the transmission of motion therebetween.
There are generally provided axial cam structures which generate axial forces dependent on the torque transmitted through the transmission and the axial forces so generated are applied to conical race rings or conical sun structures to provide the appropriate traction surface contact forces.
An arrangement in which the traction ring consists of two slightly conical rings which are forced toward each other to engage the traction rollers therebetween is shown for example in U.S. Pat. No. 4,052,915. But what is considered to be the closest art reference is applicant's published manuscript "Bearings and Rolling Traction, Analysis and Design" which is available from Excelermatic, Inc., Austin, Tex. 78731, describes, and shows in FIG. 20-3, a fixed ratio traction roller transmission mission in which the sun consists of two slightly conical sun sections which are forced toward each other to engage the traction rollers for firm torque-dependent engagement of the traction rollers with the traction ring and the sun structure.
In all these arrangements however there occurs some spin at the traction surfaces since the roller and ring traction surfaces are not quite cylindrical so that, with large contact forces, there will be some wear of the traction surfaces.
It is also noted that, with a small cone angle of the sun roller structure, there is necessarily a relatively large axial movement necessary for the conical sun portions which, in the given arrangement for example, requires cams at both sides of the sun roller structure. Larger axial camming motion can be obtained by cam structures associated with the larger-diameter traction rings as shown in U.S. Pat. No. 4,052,915, but high-speed orbiting of the traction rollers in these transmissions, especially in split-torque or regenerating planetary drives, will generate large centrifugal forces on the ring structure which may eventually overcome the cam forces on the ring structure to an extent that engagement of the planetary traction rollers with the sun roller becomes insufficient resulting in slippage between the sun roller and the planetary rollers.
It is the object of the present invention to overcome the disadvantages of the prior art arrangements.